System for mounting a tractor unit on a guide track

ABSTRACT

A mounting mechanism for connecting a tractor unit to a guide track, the mounting mechanism includes a fixed block having a first set of rolling devices and a movable plate having a second set of rolling devices. The distance between the first and second sets of rolling devices is adjustable by moving the movable plate to engage or disengage the tractor unit to the guide track. A clamping assembly is provided with a shaft, cam spring, and cam handle for adjusting the distance between the first and second rolling devices. When the cam handle is in an open position, the distance between the rolling devices is greater than the width of the guide track and when the cam handle is in a closed position the distance between the rolling devices is approximately equal to the width of the guide track.

PRIORITY

The present application is a continuation-in-part of U.S. Nonprovisionalapplication Ser. No. 13/676,170 filed Nov. 14, 2012 which claimspriority to U.S. Provisional Patent Application No. 61/561,811 filedNov. 18, 2011, the contents of which are incorporated herein byreference in their entirety.

TECHNICAL FIELD

Certain embodiments relate to welding systems, devices, and processes.More particularly, certain embodiments relate to a system and/or methodfor mounting a tractor unit on a guide track, engaging a tractor driveto a track gear, adjusting an angle of a welding head, and/or adjustinga torch lead/lag angle in any of brazing, cladding, building up,filling, hard facing overlaying, joining and welding applications.

BACKGROUND

This patent document relates to welding systems, devices, and processes.

Welding in large industrial applications, e.g., metal inert gas (MIG)and tungsten inert gas (TIG) pipe or plate welding, can involve weldingtogether very thick work pieces in e.g., an orbital welding process. Forexample, the arc weld head in an orbital welding process can be rotatedalong a guide track around the work piece, e.g., continuously rotatingthe welding head 360° around the work piece such as a pipe, or rotatingthe head around the pipe for 180° on one side of the pipe and thenrepeating head rotation on the other side of the pipe. Many weldingapplications require precision welding, from the small standardworkpieces to those of the larger scale. Welding systems can be designedto include a welding head and a guide track to which the welding head ismovably engaged, e.g., the welding head can be mounted on tractor driveunit, to move along the guide track. For example, some orbital weldingsystems can have the guide track in a ring or orbital configuration thatis engaged around a workpiece to guide the welding head to move alongthe weld gap. To fit the guide track around the workpiece, several tracksegments may be joined together to form the full guide track and tosecurely attach the guide track to the work piece, e.g., 360° around thework piece.

Accordingly, in conventional welding systems, the quality of a weld canbe affected by the manner in which a tractor unit is mounted onto aguide track because the mounting can affect how smoothly the tractorunit will travel along the guide track. For example, an improperlymounted tractor unit on a track ring can flex as it moves around thetrack ring. The flexing can cause the tungsten electrode of the weldhead that is attached to the tractor unit to move, e.g., the tungstenelectrode can angle in when the tractor unit is at the “12 o'clock”position and angle out when it is at the “6 o'clock” position. This canoccur when the tractor unit is not firmly mounted on the track, causing“crabbing” based on vibration or jerking. Additionally, mountingmechanisms can be fragile and easily damaged, e.g., binding and damageto tractor unit components can occur due to over-tightening.

In addition, improper alignment of the travel drive gear in the tractorunit to the track gear of the guide track can also cause problems withweld quality and delays in the welding process. For example, if thecenter of gravity of the weld head shifts due to, e.g., debris on thetrack gear, the gears on the travel drive gear and track gear can jam,especially if the system was not properly aligned. To reduce theproblems associated with misalignment of the travel drive gear to thetrack gear, the travel speed of conventional tractor units may need tobe set to slow.

Moreover, the mounting of the tractor unit onto guide track may becumbersome due to the weight of the tractor unit. Typically, therollers/wheels on a tractor unit need to be manually aligned before therollers/wheels can engage and clamp onto the guide track. That is, asthe tractor unit is being mounted on the guide track, an operator mayneed to physically jog the tractor unit back and forth while adjustingthe engaging mechanism until the rollers/wheels of the tractor unit areproperly aligned to the guide track. Because tractor units arerelatively heavy, the mounting process may be physically exhausting,especially if the operator has to fight gravity while mounting thetractor unit.

Further, the orientation of electrode relative to the weld puddle andthe arc length are important to producing proper welds, especially whenmechanical oscillation is used. However, conventional systems andmethods for orienting welding heads are not ideal in that they canproduce poor quality welds. For example, FIG. 12 illustrates a prior artsystem for performing a fillet weld using a gas-shielded tungsten arcwelding (GTAW) system (50). For brevity, only the components relevant tothis discussion are illustrated. The GTAW system (50) includes a weldingtorch (10) that is oriented such that the torch (10) is, for example,perpendicular to the surface of weld puddle (40) as shown by line (12).The torch (10) is connected to a welding base (30) that providesmechanical oscillation as shown by arrow (32). As the torch (10) ismoved across the weld puddle (40), the length of arc (5) will change,i.e., the distance between the tip of tungsten electrode (15) and thesurface of weld puddle (40) will change. Accordingly, to maintain theproper arc length, an arc voltage control (AVC) assembly (20) movestorch (10) in the appropriate direction along arrow (22) as themechanical oscillation moves the torch (10) in a direction (32). Thatis, the AVC assembly (20) adjusts the distance between the torch (10)and the weld puddle (40) in order to maintain the arc (5) at the desiredlength. However, because the AVC assembly stroke direction asillustrated by arrow (22) is different from the orientation of the torch(10) as illustrated by line (12), the resulting weld, can be of poorquality. In addition, poor quality welds can also occur due to limitedAVC stroke (e.g., limited to approximately 1 inch AVC stroke) and/orlimited rotation of the AVC assembly (e.g., limited to approximately 40degrees) with respect to the welding torch and/or the workpiece (weldpuddle). Further, poor quality welds can also occur if the attachmentbetween the welding torch and AVC assembly and/or the attachment betweenthe AVC assembly and the base unit are not stable due to being, e.g.,insecure and/or weak and/or if the attachments have excessive wear dueto, e.g., overuse and/or lack of durability.

Moreover, in conventional welding systems, the torch electrode lead/lagangle adjustment is limited, typically in the 0 to 5° range with some upto 12°. The limited lead/lag adjustment also limits the flexibility insetting up the welding configuration. In addition, the torch lead/lagadjustment mechanisms in conventional systems have numerousdisadvantages such as: marring of weld head components, slippage of theweld head setup due to weak locking mechanisms, difficulty in accessingthe lead/lag angle setup mechanisms, and inconsistent lead/lag anglesettings—to name just a few.

Further limitations and disadvantages of conventional, traditional, andproposed approaches will become apparent to one of skill in the art,through comparison of such approaches with embodiments of the presentinvention as set forth in the remainder of the present application withreference to the drawings.

SUMMARY

Exemplary techniques, systems, and devices are described for weldingsystems that use a guide track, e.g., a guide track having a curvedtrack rail profile. However, the exemplary embodiments discussed beloware not limited to curved track systems and can be incorporated in anymobile welding system whether it is mounted on a curved track, straighttrack, or some other type of track or in a weld head that is stationary.

In one embodiment, a mounting mechanism for connecting a tractor unit toa guide track is provided. The mounting mechanism includes a fixed blockhaving a first set of rolling devices and a movable plate having asecond set of rolling devices. The movable plate may adjusted, therebyadjusting the distance between the first and second rolling devices. Aclamping assembly is also provided to adjust the movable plate relativeto the fixed block. The clamping assembly includes a shaft extendingfrom the fixed block and through the movable plate and a cam springbetween the fixed block and movable plate for biasing the movable plateaway from the fixed block. A cam handle is connected to the shaft andmovable between open and closed positions. In the open position, thetractor unit disengages the guide track and in the closed position thetractor unit engages the guide track. When the cam handle is in the openposition, the distance between the rolling devices is greater than thewidth of the guide rail. When the cam handle is in the closed position,the distance between the rolling devices is approximately equal to thewidth of the guide rail.

In a variation of the mounting mechanism, the shaft is adjustablythreaded into the fixed block. Alternatively, an axle is providedbetween the cam handle and shaft; the axle may be adjustably threadedonto the shaft.

The shaft may include a first threaded portion for engaging the fixedblock and a second threaded portion for receiving the axle. In onearrangement, the shaft has a first thread direction for engaging theblock and a second thread direction for receiving the axle.Alternatively, the shaft may have a first thread pitch for engaging theblock and a second thread pitch for receiving the axle.

In yet another arrangement, an over-clamp spring may be provided betweenthe cam handle and movable plate. The over-clamp spring may have astiffness greater than the stiffness of the cam spring.

The first and second rolling devices are designed to roll on the trackand may include one or more pivot blocks, with one or more rollers oneach of the pivot blocks. The pivot blocks may be configured to pivotsuch that the rollers on each of the pivot blocks can conform to aprofile of the guide track as the tractor unit is engaging the guideblock. The clamping assembly is configured to operatively connect therollers of each of the pivot blocks when the clamping assembly is in aclosed position.

Each of the pivot blocks may comprise a locking mechanism configured toprevent the respective pivot blocks from pivoting once the tractor unithas engaged the guide track. The locking mechanism may be a bushingdisposed such that friction prevents the pivot blocks from pivoting whenthe tractor unit has engaged the guide track. The guide track may have,for example, a profile that is concave, convex, straight, or combinationthereof. The guide track may have rails sized between 1/16″ to 2″,inclusive. The shapes of the first and second rails of the guide trackmay be round, square, triangular, or octagonal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the invention will be more apparent bydescribing in detail exemplary embodiments of the invention withreference to the accompanying drawings, in which:

FIGS. 1A, 1B, and 1C illustrate an exemplary guide track featuring atubular track rail;

FIG. 1D illustrates an exemplary multi-point roller of a weld headtractor mount interfaced with an exemplary tubular track rail;

FIGS. 2A and 2B illustrate an exemplary mounting mechanism for a weldhead tractor unit;

FIGS. 3A and 3B illustrate an exemplary pivoting travel gear engagementfor a weld head tractor unit;

FIG. 3C illustrates an exemplary weld head tractor unit traveling alongconcave, convex, straight, and variable guide tracks;

FIG. 4 illustrates an exemplary adjustable weld head angle mechanism ofan AVC assembly of a weld head tractor unit;

FIGS. 5A and 5B illustrate an exemplary pivoting lead/lag torch anglemechanism for a welding system;

FIGS. 6A and 6B illustrate an exemplary locking mechanism that can beincorporated in the mounting mechanism of FIGS. 2A and 2B;

FIG. 7 illustrates an exemplary embodiment of a weld head angleadjustment system that has been incorporated in an orbital track-weldingsystem;

FIG. 8 illustrates an exemplary embodiment of an angle adjustmentmechanism that can be in the weld head angle adjustment system of FIG.7;

FIG. 9 illustrates an exemplary welding system that may be used in anyof brazing, cladding, building up, filling, hard-facing overlaying,joining and welding applications;

FIG. 10 illustrates an exemplary embodiment of a lead/lag torch angleadjustment mechanism that can be incorporated in the systems of FIGS.5A, 5B and 9;

FIGS. 11A to 11C illustrate exemplary embodiments of a lead/lag torchangle adjustment mechanism that can be incorporated in the systems ofFIGS. 5A, 5B and 9;

FIG. 12 illustrates a prior art welding system;

FIGS. 13A and 13B illustrate an intersection of a roller contact linewith a joint interface for the track rail of FIGS. 1A, 1B, and 1C;

FIGS. 14A and 14B illustrate exemplary pivot angles for the pivot blocksof the exemplary mounting mechanism illustrated in FIGS. 2A, 2B, 6A, and6B;

FIG. 15 illustrates an exemplary pivot block/roller arrangement that isconsistent with an embodiment of the present invention;

FIGS. 16A to 16D illustrate a tractor unit using the exemplary pivotblock/roller arrangement in FIG. 15;

FIGS. 17A to 17D illustrate exemplary serration or toothed surfaceconfigurations that can be incorporated into the angle adjustmentmechanism of FIG. 8;

FIG. 18A illustrates a front view of the tractor unit with analternative mounting mechanism in an open position;

FIG. 18B illustrates a front view of the tractor unit with thealternative mounting mechanism of FIG. 18A in a closed position;

FIG. 19 illustrates a perspective view of the latch mechanism assemblyof the alternative mounting mechanism in a closed position;

FIG. 20A illustrates a top cutaway view of the latch mechanism assemblyof the alternative mounting mechanism in an open position; and

FIG. 20B illustrates a top cutaway view of the latch mechanism assemblyof the alternative mounting mechanism in a closed position.

Like reference symbols and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

Exemplary embodiments of the invention will now be described below byreference to the attached Figures. The described exemplary embodimentsare intended to assist the understanding of the invention, and are notintended to limit the scope of the invention in any way. Like referencenumerals refer to like elements throughout.

Examples are provided to illustrate various techniques, systems, anddevices for welding systems that use a guide track with two or moretrack segments connected to guide the welding head and a welding headtractor device that drives the welding head along the guide track inperforming the welding.

A guide track with two or more track segments can be designed to allowfor easy disengagement the guide track from a work piece such as a largepipe. One of technical challenges in joining two or more track segmentsto form a guide track is the presence of a discontinuity between twojoined track segments. Such a discontinuity can affect the travel motionof the welding head by causing, e.g., a jump, interrupt, or stutter ofthe continuous motion of the welding head in the weld gap. This canadversely affect the precision of the welding operation and lead toimprecision in welding, such as degradation in the integrity andstrength of the welded joint. Imprecision in welding can have severerepercussions for a variety of welding applications. An imprecise weldcan be associated with the motion of a weld head tractor unit along aguide track (e.g., mounted around a work piece such as a pipe), whichcan be

disrupted during transition from one track segment to another tracksegment at the perpendicular joint. For example, track discontinuitiesat the track segment transition region can cause the unit to jump orstutter until the transition point has been passed, which can lead to animproper or unacceptable weld. Welding tracks that provide single-pointof contact rollers to the track rails can be susceptible to unevenregions along the guide track.

In one aspect, the disclosed technology can include a guide trackconfigured to provide a smooth interface with a weld head tractor unit(e.g., a weld head tractor for orbital welding applications) along theguide track, including a smooth and curved edge to ensure smooth motionof the weld head and a smooth and continuous transition in the interfacebetween two adjacent track segments. The curved edge of the track may bein various desired shapes and the following example employs a circularshaped edge.

FIG. 1A shows a three dimensional view of an exemplary guide track (100)that includes two track rails (110) that are configured as tubular railswith circular exterior surfaces. The two tubular track rails (110) arepositioned on the outside of the guide track (100) that is shaped as aring guide track which can be mounted to a cylindrical work piece suchas a pipe. Each tubular track rail (110) is formed by two or more tracksegments (111) and (112). A track segment, e.g., track segment (111),connects each track rail by at least one track cross member (120) thatare engaged between respective engagement locations on the two trackrails (110). Between the two track rails (110), a track gear (130) isprovided at, e.g., a middle position between the two track rails (110),for engaging the welding head tractor device that carries the weldinghead. In this example, two half-circle track segments (111) and (112)that are connected to each other at two joints (115) and (116).

FIG. 1B shows a side view of the tubular guide track (100) in FIG. 1A.In this example, each tubular track rail (110) includes a transitionbetween two track segments (111) and (112) at joint (115) that forms aninterface at an acute angle with respect to the track. The insert inFIG. 1B shows that the end facet of each track segment (111) or (112) isan angle facet and two opposing facets of the track segments (111) and(112) match each other to form the angled joint interface (117). Thisdesign provides a smooth transition across the joined region. Inoperation of a welding system with such a track, a weld head tractorunit riding along tubular track rail (110) transitions across angledjoint interface (117) of two track segments of guide track (100), thenon-perpendicular alignment of angled joint interface (117) facilitatesa nonabrupt, smooth transition from one track segment to the adjacenttrack segment to ensure a smooth and continuous weld to be filled in theweld gap. As illustrated in FIGS. 13A and 13B, the reason that anon-perpendicular transition is smoother is because the contact points(or contact line) of the rollers fall on a line that is perpendicular tothe track (see FIG. 13A). If the joint interface is also perpendicularthen all contact points of the rollers will hit the transition at thesame time and cause a jump or stutter. However, in the presentinvention, the joint interface (117) is angled. Accordingly, the rollersonly intersect the joint interface (117) at one point while stillmaintaining contact with track rail (110) at the other points along thecontact line.

Various materials can be used to form the track trails in FIGS. 1A and1B. An exemplary track rail of the disclosed technology can be of ametal, polymer, ceramic, or a composite material. The shape of theexemplary track rail can include a tubular geometry with a circularcross section, which can be hollowed, filled, or partially filled. Othershape of the exemplary track rail can include a rectangular or squareshape with curved or rounded edges, in which one, two, three or fouredges are rounded to any of a multitude of degrees of curvature, and thetrack rail can be hollowed, filled, or partially filled. The exemplarytrack rail can include other shapes in which the leading edge includes acurved contour. The curved contour shape of the exemplary track rail canincrease the surface area between the track rail and the tractor unit(e.g., increasing the number of contact points, providing more supportto the tractor unit by the track rail.

FIG. 1C shows another side view of guide track (100), which shows tracksegment (111) that includes track cross member (120) between multipletrack rails, e.g., the two track rails exemplified by track rails (110).Track cross member (120) can connect the two track rails (110) such thatthey are aligned substantially parallel with each other. Track segment(111) shown in FIG. 1C includes multiple track cross members connectingthe track rails (110). Track cross member (120) can also attach a trackgear, such as the gear ring shown as track gear (130). Track segment(111) also includes multiple track cross members connecting the trackgear (130).

FIG. 1D shows the exemplary tubular track rail (110) that features arounded shape or geometry, which can provide multiple points of contactto a mounting component of a weld head tractor unit, e.g., mountingcomponent (150), for moving the weld head along the track rail (110).The exemplary mounting component (150) can include rollers or wheels(that interface with tubular track rail (110) at multiple points ofcontact (or contact line) (161). Two multi point rollers (160) are shownin FIG. 1D for contacting the track rail (110) and for rolling againstthe curved surfaces of the track rail (110) as part of mountingcomponent (150). In this example, the multi point rollers (160) areconnected to a pivot block (170) and can rotate around their respectiveroller rotation axis (165) when rolling along a track rail (110). Theexemplary tubular track rail (110) of guide track (100) can providemultiple points of connection with the weld head tractor unit such thatwhen the unit transitions across joints of the guide track, a consistenttravel is facilitated. The tubular geometry of the track rail can enablean interface that allows for mounting component (150) to be in contactat multiple points, which can prevent the tractor unit from traveling inan undesired position, e.g., jumping, stuttering, or swerving to theleft or the right due to discontinuity. For example, multi point roller(160) can travel along the track having multiple points of contact (161)so that at transition from one segment to the other (e.g., at angledjoint interface (117)), there can be fewer disturbances than if thetrack segments were joined perpendicularly to each other.

The disclosed technology includes a tubular track that can usemultipoint contact wheels and an angled and/or gradual transition jointthat provides a smooth transition of a mounted device (e.g., a weld headtractor unit), which can significantly reduce undesired motions of themounted device, e.g., swerves, jumps and stutters. This can provide ahigher precision weld by significantly reducing abrupt, discontinuousmotion of the weld head in the weld joint. Additionally, the exemplaryguide track can have a reduced overall weight by using tubular membersthat are joined by cross members, rather than using a solid rectangularshaped track. The exemplary guide track can be manufactured with areduced amount of material (e.g., that can be hollow or partiallyfilled). For example, an exemplary guide track can have a reduced weightbased on the geometry and/or material of the track rails, by reducingthe amount of volume and/or density of the overall guide track. Anadvantage of reduced weight can include making it easier in moving theexemplary guide track to the next welding position. Additionally,reduced weight can also improve manufacturability, for example, bymaking the guide track out of multiple, smaller, less complicated parts,rather than one complex part. For example, manufacturability of anexemplary guide track can be made easier by forming steel tubing becausethe steel tube can be finished in one machining operation, for example,rather than three machining operations that a typical one-piece trackwould require. Cross member sections can be designed to work for anydiameter size, e.g., with only two feature dimension alterations. Theexemplary guide track can offer long lasting durability due to itstubular configuration. The tubular configuration provides a smoothcircular contact surface that allows significantly reduced frictions.For example, the exemplary guide track can be of a steel material, suchthat in rugged environments the exemplary guide track can withstanddings and nicks, such that such dings and nicks to the track (e.g.,tubular track rails) would not affect the motion of a mounted weld headtractor unit. The exemplary track guide can include a track gear withgear profiles that can provide smoother tractor motion. Also, theexemplary guide track of the disclosed technology can reduce weldingsystem “set-up” factors, such as time and quantity and complexity ofcomponents.

Exemplary embodiments of the present invention can include a tractormounting mechanism for a weld head tractor unit that enables the tractorunit to be mounted onto track rails that can have different shapesand/or sizes.

FIG. 2A illustrates a weld head tractor unit (200) with a tractormounting mechanism that includes a track rail clamping assembly (240),which is shown in the unclamped position in FIG. 2A. As seen in thefront view of the figure, in the unclamped position, the tractor unit(200) can be movably mounted to a guide track (e.g., guide track (100))using a rolling device or rolling devices such as, e.g., wheels and/orrollers. The rail clamping assembly (240) includes a clamping mechanism(220) that is operatively connected to wheel/roller set A. To mount ordismount the tractor unit (200), the clamping mechanism (220) can beturned such that the rail clamping assembly (240) retracts wheel/rollerset A (see front view of FIG. 2A). As part of the exemplary mountingmechanism, in some embodiments, the tractor unit (200) can be clamped orunclamped with the use of a single clamping action, i.e., by turning theclamping mechanism (220) to operate wheel/roller set A.

The exemplary mounting mechanism can also include multiple opposingwheels and/or rollers (210), e.g., wheel/roller sets A and B, which canconform to the track rails, e.g., track rail (110), which can be tubularor solid. The total number of wheels and/or rollers (210) on tractorunit (200) can be, e.g., eight. However, the tractor unit can have moreor less wheels and/or rollers (210). In some embodiments, the wheelsand/or rollers (210) can be mounted on pivot blocks (211). Each pivotblock (211) can have at least one wheel or roller (210). For example, insome embodiments, each pivot block (211) has two wheels or rollers(210). Thus, the exemplary eight wheels/rollers (210) can include foursets of pivoting blocks (211) with two wheels/rollers mounted at eachblock. Of course, the number of pivot blocks (211) and the correspondingnumber of wheels/rollers (210) will depend on a number of factors suchas the size and weight of the tractor unit (200), the size of thediameter of the track rails (110), the size of the wheels/rollers (210),etc. However, for typical track-mounted welding applications. e.g.,orbital welding applications, it is contemplated that four pivot blocks(211) will be used, each block (211) having two wheels/rollers (210) anddisposed, e.g., on a corner of tractor unit (200) (see, e.g., FIG. 6B).The pivot blocks (211) each include a central bearing that allows therespective pivot block (211) to pivot when the tractor unit (200) isunclamped. The angle of pivot is not limiting. However, to facilitatethe mounting of the tractor unit (200) onto the track rails (110), thepivot blocks (211) can be limited to an inward pivot angle of up to 26°(see FIG. 14A) and an outward pivot angle of up to 10° (see FIG. 14B)with respect to a centerline between two pivot blocks (211). Thispivoting movement can allow the rollers (210) to immediately conform toany profile of track rail (110), e.g., concave, convex, straight, or anycombination thereof. The size and shape of the track rail (110) are notlimiting and the size of the track rail (110) can range from, e.g., 1/16inch to 2 inches and the shape can be, e.g., round, square, triangle,octagonal, or some other shape. Of course, the shape of the wheelsand/or rollers (210) may change based on the size and shape of the trackrail (110). In addition, the track rail (110) can be either tubular orsolid. Further, the guide track (100) configuration is not limited tobeing a ring and can be, e.g., any of the track configurationsillustrated in FIG. 3C, i.e., the convex guide track (391), the concaveguide track (392), the straight guide track (393), and the variableguide track (394), or some other type of track configuration.

When the tractor unit (200) is clamped, the exemplary mounting mechanismcan include a locking mechanism to lock the pivot blocks (211) in place.For example, in some embodiments, each pivot block (211) can have alocking bushing (213), which enables free movement with no pressure(e.g., when the tractor unit (200) is unclamped) and then locks down toa firm location once the tractor unit (200) is clamped. For example, insome embodiments, the bushing (213) can be disposed such that, when thetractor unit (200) is clamped, the bushing is pressed between a sidewall of the tractor unit (200) and the rollers (210) as illustrated inFIGS. 6A and 6B. When clamped, the force on the bushing (213) is suchthat the friction holds the corresponding pivot block (211) in place asthe rollers (210) roll on track rail (110). In some embodiments, thelocking bushing (213) can be made of bronze or some other appropriatematerial. When the tractor unit (200) is unclamped, the pivot block(211) is free to pivot and conform to any profile of track rail (110),e.g., concave, convex, straight, or any combination thereof. This designfacilitates full contact of the tractor unit (200) with the track rails(110) and smooth movement of the tractor unit (200). Additionally, insome embodiments, an engagement point of the tractor drive gear (310)(see also FIG. 3A) can be directly aligned with the axis of the pivotbearings of the two front pivot blocks, e.g., the pivot blocks (211)that are located next to the travel drive gear (310). This featureenables the tractor unit (200) to conform to any track rail (110) withno additional adjustment or modifications to the tractor unit (200). Theorientation of travel drive gear (310) to the front support pivotblocks, e.g., pivot blocks (211), can be configured to remain the sameon all track configurations.

As discussed above and seen in the side view and cross-sectional topview of FIG. 2A, a clamping mechanism (220) of the rail clampingassembly (240) can engage the pivot blocks (211) of wheel/roller set A.In some embodiments, the clamping mechanism (220) is manually operatedand can include rotating knobs (221) to facilitate quick manual turning.In some embodiments, the clamping assembly (240) can include a heavyduty screw (222). The clamping assembly (240) can include a clutch orequivalent mechanism such that the screw (222) cannot be over tightened(manually or otherwise). The rail clamping assembly (240) also includesa movable side plate (224) on which, e.g., two pivot blocks (211) ofwheel/roller set A are mounted. In some embodiments, the movable sideplate (224) can be configured to slide accurately on linear bearings,e.g., the four linear bearings (230). Of course the present invention isnot limited to the use of linear bearings (230) and/or screw (222) toengage and disengage roller set A and other methods can be used.

In the fully unclamped position, the distance from the movable sideplate (224) of the exemplary mounting mechanism to the exemplary guidetrack (100) is wide enough so that the wheels/rollers (210) are nottouching the track rails (110). That is, in the fully unclampedposition, there is enough clearance between the wheels/rollers (210) andtrack rails (110) such that the tractor unit (200) can be dismountedwithout interference from track rail (110). In order to clamp or engagethe wheels/rollers (210) to the track rails (110), as seen in FIG. 2B,the clamping mechanism (220) can be operated such that the pivot blocks(211) including the rollers (210) move toward the track rails (110).Once the wheels and/or rollers (210) contact the track rails (110), thepivot blocks (211) are free to pivot such that the wheels and/or rollers(210) conform to any profile of track rail (110), e.g., concave, convex,straight, or any combination thereof. Once the clamping mechanism (220)fully engages the rail clamping assembly (240) to the track rails (110),the locking bushing (213) prevents the pivot blocks (211) from moving asdiscussed above. In some embodiments, when clamped, the surface of eachwheel/roller (210) can have multiple points of contact (215) with trackrail (110), e.g., from two points to a line of contact. Of course, inother embodiments, the wheels/rollers (210) may contact track rail (110)at only one point. In the above embodiments, wheel/roller set A wasmoved to clamp or unclamp tractor unit (200) from guide track (100).However, the present invention is not limited to just movingwheel/roller set A, and wheel/roller set B or both wheel/roller sets Aand B can be operated by clamping mechanism (220) to clamp or unclamptractor unit (200) to/from the guide track (100).

The exemplary mounting mechanism of the disclosed technology can provideconvenient and easy mounting of a weld head onto different profiles,shapes, and sizes of track rails, which can eliminate the need toperform multiple adjustments for each track configuration. The exemplarymounting mechanism as discussed above includes a quick and elegant wayto mount a tractor unit (200) with a single adjustment (e.g., track railclamping assembly (240) using clamping mechanism (220)) such that noadditional adjustments are necessary. Exemplary embodiments of themounting mechanism discussed above can provide advantages such asreducing and/or removing flexing of and wear on a weld head tractor unitand other components, and enabling very smooth movement of the weld headtractor unit along a guide track at any speed, e.g., at low and highspeeds. Additionally, implementation of the exemplary embodiments of themounting mechanism discussed above can allow any size/weight tractorunit to be mounted, be handled in conditions that are extremely ruggedor at high risk of abuse, and be easily clamped and unclamped to theguide track.

In another aspect, the disclosed technology can include a tractormounting mechanism capable of mounting a weld head tractor unit tomultiple shapes and sizes of a welding track rail.

The manner in which a weld head tractor unit is mounted onto a guidetrack can be associated with the quality of the weld based on the degreeof smoothness of the motion of the tractor unit along the guide track.For example, a weld head can flex on a track ring, which can causetungsten to angle in at “12 o'clock” and angle out at “6 o'clock.” Thismay occur when the weld head is not firmly mounted on the track, causing“crabbing” based on vibration or jerking. Additionally, mountingmechanisms can be fragile and easily damaged, e.g., binding and damageto weld head components can occur due to over tightening.

FIG. 2A shows an exemplary mounting mechanism of an exemplary weld headtractor unit (200) that includes a side wheel track roller clampingassembly, shown in the unclamped position. As seen in the front view ofthe figure, the tractor unit (200) can be mounted to a guide track(e.g., guide track (100)) with the use of a single clamping action aspart of the exemplary mounting mechanism. The exemplary mountingmechanism can include multiple opposing wheels and/or rollers, e.g.,eight opposing wheels/rollers (210), which can conform to the trackrails, e.g., tubular track rail (100). The exemplary eightwheels/rollers (210) can include of four sets of pivoting blocks (211)with two rollers/wheels mounted on each block. The pivoting blocks eachon their own central bearing can immediately conform to any size andshape of track. Each pivot block can have a locking bronze bushing whichenables free movement with no pressure and then locks down to a firmlocation once clamped. This design facilitates full contact the tractorunit with the track rails and smooth movement of the tractor unit.Additionally, an engagement point of the tractor drive gear can bedirectly aligned with the axis of the pivot bearings of the two frontpivot blocks. This feature enables the tractor to conform to any trackwith no additional adjustment or modifications to the tractor). Theorientation of drive wheel to the front support pivot blocks, e.g.,pivot blocks (211), can be configured to remain the same on all trackconfigurations. As seen in the side view and crosssectional top view ofFIG. 2A, a clamping mechanism (220) with two rotating knobs can engagethe four pivot blocks (211) with quick manual turning. Clampingmechanism (220) can include a heavy duty screw which cannot manually beover tightened. The movable side plate on which two pivot blocks aremounted can be configured to slide accurately on four linear ballbearings, e.g., linear bearings (230). In the unclamped position, thedistance from the exemplary mounting mechanism to the exemplary guidetrack (100) is wide enough so that the wheels/rollers (210) are nottouching the track rails (110). In order to clamp the rollers (210) tothe track rails (110), as seen in FIG. 2B, the clamping mechanism (220)can bring the pivot blocks (211) including the wheels/rollers (210)toward the track rails (110). When clamped, the wheels are interfaced tothe track rail having multiple points of contact. The mounting mechanismcan be configured to clamp all the wheels/rollers (210) together.

The exemplary mounting mechanism of the disclosed technology can provideconvenient and easy mounting of a weld head onto different shapes andsizes of track rings, which can eliminate the need to perform multipleadjustments for each track configuration. The exemplary mountingmechanism includes quick and elegant way to mount a tractor unit with asingle screw wheel (e.g., mounting knob (220)) such that no additionaladjustments are necessary. This can provide advantages, such as reducingand/or removing flexing and wear, and enabling very smooth movement of aweld head tractor unit along a guide track at any speed, e.g., at lowand high speeds. Additionally, implementation of the mounting mechanismcan allow any size/weight tractor to be mounted, be handled inconditions that are extremely rugged or at high risk of abuse, and beeasily clamped and unclamped to the guide track.

In some embodiments, the rollers (210) are sized to facilitate themounting of tractor unit (200) onto guide track (100). For example, asillustrated in FIG. 15, the wheel/rollers (210) on each pivot block(211) can have different widths. The wheel/roller (210B) can have awidth (W2) that is smaller than the width (W1) of roller (210A). Thewidths (W2) and (W1) are set such that, when the clamping mechanism(220) puts the tractor unit (200) in the unclamped position, the trackrails (110) of guide track (100) can slide past wheels/rollers (210B),but not wheels/rollers (210A).

For example, as illustrated in FIG. 16A, the wheels/rollers (210A) arelocated in the inner portion of tractor unit (200) and thewheels/rollers (210B) are located on the outer portion. When the tractorunit (200) is in the unclamped position, the distance between opposinginner wheels/rollers (210A) is D1, and the distance between opposingouter wheels/rollers (210B) is D2. Because the widths of the outerwheels/rollers (210B) are set smaller than the widths of the innerwheels/rollers (210A), the distance D1 is smaller than the distance D2.The distance D2 is set such that it is slightly larger than the widestportion of track rail (110) and the distance D1 is slightly less thatthe widest portion of track rail (110).

For example, as shown in FIG. 16A, the track rails (110) are set suchthat the distance between the outermost portions of the track rails(110) is D3. Accordingly, the unclamped position of tractor unit (110)is set such that the distance D2 is greater than the distance D3 and thedistance D1 is less than the distance D3. Therefore, when the tractorunit (200) is initially mounted on the guide track (100), the outerwheels/rollers (210B) will fit over the track rails (110) as shown inFIG. 16B. The tractor unit (200) will then rest on the innerwheels/rollers (210A) as they contact the track rails (100) as shown inFIG. 16C. The width (W1) of inner rollers (210A) is set such that thetractor unit (200) can safely rest on the portion of wheels/rollers(210A) that makes contact with guide rails (110). Once the tractor unit(200) is resting on the track rails (110), the clamping mechanism (220)can be operated to clamp the tractor unit (200) to guide track (100). Asthe clamping mechanism (220) is being operated, the track rails (110)and the wheels/rollers (210A) and (210B) will be guided into the properalignment due to the tapered shape of the inner wheels/rollers (210A) asshown in FIG. 16D. While being clamped, the pivot block (211) withwheels/rollers (210A) and (210B) will operate as discussed above. Ofcourse, the width (W2) of wheels/rollers (210B) is set such that, whenclamped, there is sufficient contact area between wheels/rollers (210B)and track rails (110) that the tractor unit (200) can be safelyoperated.

The clamping mechanism (220) can be configured such that the unclampedposition sets the proper distances D1 and D2 on wheels/rollers (210A)and (210B), respectively, for track rails (110) having a width D3. Insome embodiments, the clamping mechanism (220) has multiple unclampedsettings corresponding to track rails (110) of different widths D3. Thatis, a single tractor unit (200) can be configured to clamp onto guidetracks (100) having varying width D3, which can range from, e.g., 2 to12 inches. A single tractor unit (200) can be configured to clamp ontoall or just some of the guide tracks (100) that fall within this range.Of course, other widths and ranges are possible. In some embodiments, anindicator or an operator configurable stop (not shown) can beincorporated into the clamping mechanism (220) such that the clampingmechanism (220) can be reliably opened to the corresponding width D3 ofthe different guide tracks (100). Thus, exemplary embodiments of thepresent invention allow the tractor unit (200) to be clamped to theguide track (100) without initially having to align the tractor unitrollers (210) to the track rails (110). In addition, the operator doesnot have to worry about the tractor unit slipping past the innerwheels/rollers and causing damage to travel drive gear and/or track gearwhen mounting or dismounting the tractor unit.

In some exemplary embodiments, the present invention can include atravel drive gear engagement mechanism for a weld head tractor unit thatcan, among other things, easily engage and disengage the tractor unit'stravel drive gear to a track gear so that an operator can rapidlyposition the weld head tractor unit and operate the tractor unit at anydesired travel speed, e.g., slow or fast. FIG. 3A illustrates a tractorunit (300) that can be mounted on a guide track, e.g., guide track (100)as illustrated in FIGS. 1A-1C. The guide track (100) includes a trackgear (130), which is engaged by the travel drive gear (310) of thetractor unit (300). The travel drive gear (310) and the track gear (130)can have an optimal mesh configuration to smoothly move the tractor unit(300) along guide track (100). It should be noted that, although theexemplary embodiments are described in terms of a tractor unit (300)that mount on guide track (100), the present invention is not limited inthis manner as the exemplary travel drive gear engagement mechanism canbe incorporated in other types of tractor units, not just ones thatmount on the type of guide tracks illustrated in FIG. 1. Additionally,the present invention can be used on guide tracks of a variety ofconfigurations. For example, as illustrated in FIG. 3C, a tractor unitthat includes exemplary embodiments of the travel gear engagementmechanism as discussed further below, can exhibit smooth travel alongconvex guide track (391), concave guide track (392), straight guidetrack (393), and variable guide track (394)—to name just a few.

As illustrated in FIGS. 3A and 3B, the travel drive gear engagementmechanism can include a clutch lever (320) that, when operated, quicklyengages or disengages the travel drive gear (310) to/from track gear(130). For example, in some embodiments, when the clutch lever (320) isrotated to a first position (see FIG. 3A), a connecting member (311)engages the travel drive gear (310) to track gear (130), and when theclutch lever (320) is rotated to a second position (see FIG. 3B), theconnecting member (311) disengages the travel drive gear (310) fromtrack gear (130). In some embodiments, the connecting member (311)includes a pivot point and a pivot pin (312). The pivot pin (312) isoperatively connected to the connecting member (311) such that theconnecting member (311) is pivoted in a rocking-like motion around thepivot pin (312) to engage/disengage the travel drive gear (310) to/fromthe track gear (130). For example, a first end of the connecting member(311) may be pivoted by a clutch arm (321) while a second end of theconnecting member (311), which is operatively connected to travel drivegear (310), engages/disengages the drive gear (310) to/from track gear(130). In still other exemplary embodiments, the clutch lever (320)includes an eccentric cam portion (320A) that is operatively connectedto the clutch arm (321) at a point on the cam portion (320A) that isoffset from the center of its elongated portion (see FIGS. 3A and 3B).In some embodiments, the clutch arm (321) is connected to the camportion (320A) at a point that is on the centerline of the elongatedportion of the cam portion (320A). Accordingly, due to this offset camconfiguration, as the clutch lever (320) is moved to the first position,the clutch arm (321) pivots the connecting member (311) such that thedrive gear (310) is engaged. Similarly, due the offset camconfiguration, the connecting member (311) will disengage when theclutch lever (320) is moved to the second position. Thus, the exemplaryclutch lever (320) configuration allows an operator to quickly releasethe tractor unit (300) and if necessary, reposition it on the guidetrack (100) at any time. In addition, when the cam portion (320A) ismoved to the first position, the cam goes over the centerline of itselongated portion such that the tendency for the clutch lever (320) isto stay down against the tractor unit (300) rather than open towards thesecond position. Accordingly, the cam (320A) can be shaped such that theclutch lever (320) does not inadvertently move out of position if thetractor unit (300) is jarred, e.g., due to debris on the track gear(130). In some embodiments, the clutch lever (320) is easily accessibleto the operator, e.g., located on the top of the weld head tractor unit(300). However, the clutch lever (320) may be located anywhere ontractor unit (300) as long as the location does not interfere with thetravel of tractor unit (300) or welding operations. In addition,although some embodiments of the engagement mechanism use a single pivotpoint, the present invention is not limited in this manner and thelinking mechanisms between clutch lever (320) and drive gear (310) caninclude any number of pivot points or no pivot points.

In some embodiments, the travel gear engagement mechanism can include anengagement biasing mechanism (313) that puts a biasing force on drivegear (310) so that it stays engaged with track gear (130). In someembodiments, the engagement biasing mechanism (313) permits the drivegear (310) to retract enough to drive over debris on track gear (130) tohelp alleviate problems such as gears jamming and/or the welding headshifting on tractor unit (300). After the drive gear (310) clears thedebris, the engagement biasing mechanism (313) can help drive gear (310)reengage with track gear (130). In some embodiments, the engagementbiasing mechanism (313) is located such that it is operatively connectedto the connecting member (311) where the clutch arm (321) is attached(see FIG. 3A). Of course, the engagement biasing mechanism (313) can belocated at other points in the travel gear engagement mechanism as longas a biasing force is put on drive gear (310) to engage with track gear(130). In some embodiments, the engagement biasing mechanism (313) canbe comprised of at least one spring, but in other embodiments, othertypes of biasing devices can be used. In some embodiments, the travelgear engagement mechanism can also include a refraction biasingmechanism (314) to ensure that the drive gear (310) stays disengagedfrom track gear (130). In some embodiments, the retraction biasingmechanism (314) is located such that it is operatively connected to theconnecting member (311) where the clutch arm (321) is attached (see FIG.3B). Of course, as with the engagement biasing mechanism (313), therefraction biasing mechanism (314) can be located at other points in thetravel gear engagement mechanism as long as there is a biasing forcethat ensures that drive gear (310) remains disengaged from track gear(130) when in the disengaged position. In some embodiments, theretraction biasing mechanism (314) can be comprised of at least onespring, but in other embodiments, other types of biasing devices can beused.

The type of gear configuration for the travel drive gear (310) and trackgear (130) is not limiting, e.g., spur gear, worm gear, etc., as long asthe drive gear (310) can move the tractor unit (300) along guide track(100). In some embodiments, as seen in FIG. 6A, the travel drive gear(310) includes a drive gear portion (315) and at least one drive rollerportion (316) on at least one side of the drive gear portion (315). Theconstruction of the drive roller portion (316) and drive gear portion(315) is not limiting in that the drive gear portion (315) and the atleast one drive roller portion (316) can be an integral unit or separatecomponents that have been operatively attached. In some embodiments, thegear portion (315) is a spur gear and the dimensions of the rollerportion(s) (316) correspond to the pitch diameter of the spur gear. Asillustrated in FIG. 1C, the track gear (130) can include a track gearportion (131) that is configured to mesh with the drive gear portion(315), e.g., the spur gear, of the travel drive gear (310). In someembodiments, the track gear (130) includes a land portion (132). Theland portion (132) can be on one or both sides of track gear portion(131). In some embodiments, the land portion(s) (132) and/or driveroller portion(s) (316) are configured such that the roller portion(s)(316) is(are) in contact with the land portion(s) (132) when the traveldrive gear (310) is engaged to the track gear (130). In someembodiments, the land portion(s) (132) will correspond to the pitchdiameter of the track gear portion (131) for guide tracks that arecurved, or to the pitch line of the track gear portion (131) for guidetracks that are straight. In some embodiments, the dimensions of theland portion(s) (132) and the drive roller portions(s) (316) correspondto the respective pitch diameter(s)/line, thus ensuring proper alignmentof the drive gear portion (315) to the track gear portion (131) whenengaged. That is, for a curved track gear portion (131), the diameter ofthe land portion (132), which equals the pitch diameter of the trackgear portion (131), will correspond to the diameter of the drive rollerportion (316), which equals the pitch diameter of the drive gear portion(315). For a straight track gear portion (131), the dimension of theland portion (132), which equals the pitch line of the track gearportion (131), will correspond to the diameter of the drive rollerportion (316), which equals the pitch diameter of the drive gear portion(315). The proper alignment ensures that there is no gear backlash andthe tractor unit (300) sees a smooth, stable operation at all operatingspeeds. In addition, a drive roller (316) that rolls on the landportion(s) (132) also prevents the drive gear portion (315) from jamminginto the track gear (130) due to the biasing force from the engagementbiasing mechanism (313) or due to over-tightening. This preventsexcessive wear and binding of the drive mechanism. In some embodiments,the travel drive unit (310) is configured such that it includes a driveroller portion (316) on each side of drive gear portion (315) and thetrack gear (130) is configured such that one land portion (132) islocated on one side of gear portion (131). Such a configurationmaintains proper mating with the drive gear (310) and enables thetractor unit (300) to be mounted in either orientation with respect totrack guide (100).

In another aspect, the disclosed technology can include a tractor unitdrive pivoting travel gear engagement mechanism for engagement anddisengagement of a weld head tractor unit to a guide track. Excessiveslop or backlash in a gear drive of a weld head tractor unit mounted toa guide track can cause improper travel motion as the weld head positionshifts and the loading direction on the drive gear changes, which canlead to inconsistent travel speed. In order to avoid improper motion,some methods can include eliminating the backlash between the drive gearand the track gear.

The exemplary drive pivoting travel gear engagement mechanism can allowfor the travel motor to be easily engaged and disengaged with a quickrelease lever, so that an operator can rapidly locate the weld head onthe track. In addition, the quick release mechanism allows for greaterflexibility in optimizing the travel speed of the tractor, as thegearing of the tractor unit no longer has to be set at a fast travelspeed for locating the weld head. That is, if a tractor unit does nothave a quick release mechanism, the motor gearing is set to drive thetractor unit very fast in order to minimize the time to properlyposition the weld head on the track for the start of, e.g., weldingoperations. However, when the gearing is set for very fast travel, therecan be problems when driving the tractor unit at slower speeds. With thequick release lever of the present invention, the tractor unit can belocated at the proper position on the track (or very close to the properposition) with the travel gear disengaged. Thus, the travel gear can beoptimized for, e.g., welding operations rather than for locating theweld head on the track. FIG. 3A shows an exemplary weld head tractorunit (300) with an exemplary drive pivoting travel gear engagementmechanism mounted on a guide track (e.g., guide track (100) thatincludes track gear (130)), e.g., in an engaged position. The exemplarydrive pivoting travel gear engagement mechanism can include a lever(320) on top of the weld head tractor unit (300) through an eccentriccam that raises and lowers a drive gear (310). As seen in the front andside views of FIG. 3A, drive gear (310) can be engaged with a driveassembly as part of track gear (130), such that the engagement can occurin a rocking-like motion of drive gear (310) on a single pivot rod(311), which can pivot along a pivot pin (312). The exemplary pivotingtravel gear engagement mechanism also can include a spring (313) to keeppressure on the drive gear (310), e.g., when it is engaged with theguide track (e.g., track gear (130)) as shown in FIG. 3A. Drive gear(310) can be retracted from the guide track by raising lever (320),which can cause a spring (314) to release pressure and pivot away fromengagement, as seen in the front and side views of FIG. 3B. Drive gear(310) can include a plurality of pitch spokes. The pitch diameter of thespokes is not limiting and can be any desired pitch diameter, and canvary from one tractor unit to another. The geometry of a pitch spoke canbe, e.g., an involute curve, such that the diameter of a cross sectionat the apex of the pitch spoke is smaller than the diameter of a crosssection at the base of the pitch spoke. However, the geometry of thepitch spoke is not limiting and the pitch spoke can have othergeometries, e.g., conical. Additionally, drive gear (310) can include apitch diameter roller on both sides of the drive gear and on one side ofthe track gear, which can be configured to maintain proper mating withthe drive gear and enable the tractor to mount on either side of thetrack.

The exemplary pivoting travel gear engagement mechanism can exhibit thefollowing features and advantages, which include a quick release andrepositioning of a weld head on a guide track by use of an easilyaccessible lever, e.g., lever (320); a tractor unit with the exemplarypivoting travel gear engagement mechanism can ride over debris on thetrack gear (e.g., track gear (130)) without jamming, and then drop backinto its correct location; and a tractor unit with the exemplarypivoting travel gear engagement mechanism can be configured to maintainan exact gear pitch diameter distance between gears so there is minimalgear backlash at various positions. For example, substantially zerobacklash can result in very smooth stable travel in slow and rapidspeeds. Additionally, the exemplary pivoting travel gear engagementmechanism can allow travel along guide tracks of a variety ofconfigurations, as seen in FIG. 3C. For example, tractor unit (300) thatincludes the exemplary pivoting travel gear engagement mechanism canexhibit smooth travel along convex guide track (391), concave guidetrack (392), straight guide track (393), and variable guide track (394).

In some exemplary embodiments, the present invention can include a weldhead angle adjustment mechanism for a weld head to set the angle betweenthe weld head and a workpiece, i.e., a weld puddle on the workpiece. Asillustrated in FIG. 7, exemplary embodiments of the weld head angleadjustment mechanism can be incorporated in a weld head (760) that isoperatively connected to a welding base unit (750). The welding baseunit (750) can have a fixed relationship to the workpieces (705A and705B). Accordingly, the angle between the weld head (760) and thesurface of a weld puddle (740) of the workpieces (705A and 705B) can beadjusted by adjusting the angle between the weld head (760) and weldingbase unit (750). The weld head (760) can include an AVC assembly (710)and a welding torch (715). The AVC assembly (710) is operativelyconnected to the welding torch (715), and can include an AVC assemblycontrol unit (not shown) that is configured to maintain a desired arclength (x) extending from the tip of the torch electrode (717) to thesurface of the weld puddle (740) of workpieces (705A and 705B), which inthis exemplary embodiment, are pipes of different diameters. Of course,the present invention is not limited to use on pipes, but can be used onany desired workpiece. The AVC assembly control unit maintains the arclength (x) by moving torch (715) in the direction of arrow (712). Thearc length (x) is not limiting and can be any desired length that isappropriate for the welding parameters. In some embodiments, the weldhead (760) can include other components such as a wire feeder and wireguide (both not shown) but, for brevity, only those components relevantto the present invention will be discussed.

The weld head (760) includes weld head angle adjustment mechanism (720),which adjusts the angle between the weld head (760) and the welding baseunit (750). In some embodiments, the angle adjustment mechanism (720)connects the welding head (760) to the welding base unit (750) at asingle pivot point (765). The welding base unit (750) can be a driveunit, e.g., an orbital tractor drive, that is configured to move theweld head (760) with torch (715) along the circumferential weld jointcreated by the workpieces (705A and 705B). Of course, in situationswhere the weld head (760) is to remain stationary as the workpiecemoves, the adjustment mechanism (720) may connect the weld head (760) toa stationary welding base unit (not shown), rather than to a mobiledrive unit, e.g., welding base unit (750). The welding base unit (750)(or some other device) can be configured to provide mechanicaloscillation as shown by arrow (752) to provide the desired weld weavepattern.

The angle adjustment mechanism (720) may be designed to adjust an angleα between the welding head (760) and the welding base unit (750). Thefreedom of movement of welding head (760) may be any desired range,e.g., up to 90 degrees, up to 140 degrees, or up to 180 degrees. In someembodiments, the angle adjustment mechanism (720) can adjust the angle αbetween welding head (760) and the base unit (750) from −30 degrees to+150 degrees, and in other embodiments from −30 degrees to +110 degrees.As illustrated in FIG. 8, in exemplary embodiments of the presentinvention, the angle adjustment mechanism (720) includes a bolt (722).The bolt (722) is operatively connected to the weld head (760) and baseunit (750) such that, when the bolt (722) is tightened, the angularposition of welding head (760) with respect to the base unit (750) isfixed, and when the bolt (722) is loosened, the angle α between thewelding head (760) and the base unit (750) can be adjusted. In someembodiments, the bolt (722) can have threads (724) that thread into thewelding head (760) and/or the base unit (750). In some exemplaryembodiments, the angle adjustment mechanism (720), the welding head(760), and/or the base unit (750) can include a locking mechanism sothat the angular position of weld head (760) with respect to base unit(750) remains firmly fixed (e.g., when the bolt (722) is tightened), andan exact angle is maintained even under heavy load or abuse. Forexample, the locking mechanism can include interlocking surfaces, e.g.,serrated or toothed surfaces (721) that interlock when pressed together.In some embodiments, at least one serrated or toothed surface (721) isbuilt into at least one of the adjustment mechanism (720) (e.g., thebolt (722)), the weld head (760), and the base unit (750). For example,as illustrated in FIG. 8, the weld head (760) and the base unit (750)each have a built-in serrated or toothed surface (721). In someembodiments, the serrated or toothed surfaces (721) can directlyinterlock with each other. In other embodiments, a washer or plate (725)is disposed between the serrated or toothed surfaces (721). In someembodiments, the washer or plate (725) can be made of a material (e.g.,brass, copper, plastic, nylon, etc.) that is softer than the serrated ortoothed surfaces (721) such that the serrations embed into the washer orplate (725) to firmly lock the weld head (760) to the base unit (750).Because the washer or plate (725) is made of a softer material, anysigns of wear in the locking mechanism will first be seen by the washeror plate (725), rather than the serrated or toothed surfaces (721).Accordingly, because the washer or plate (725) can be made ofinexpensive materials that can be easily replaced after showing signs ofwear, the locking mechanism will remain durable and stable even afterrepeated use. The design of the bolt (722) with respect to size andmaterial will depend on the size and weight of the weld head (760) andthe welding environments in which the present invention will operate.However, it is contemplated that, in most cases, a large, heavy-dutybolt made of high-strength carbon steel, stainless steel, or otherhigh-strength materials will be used.

FIGS. 17A to 17D illustrate exemplary serrated or toothed surface (721)configurations that are consistent with the present invention. FIG. 17Aillustrates a configuration where the tooth configuration is V shaped.Each V-groove is cut straight across as shown in section A-A by keepingthe depth of the cutting tool constant. Because the depth of the cut isconstant, manufacturing the serrated or toothed configuration in FIG.17A is relatively easy.

Another exemplary embodiment of a serrated or toothed surfaceconfiguration is illustrated in FIG. 17B. As in the previous embodiment,the tooth configuration is V-shaped. However, in this embodiment theV-groove is cut at an angle (A) as shown in section A-A. The angle θdepends on the number of teeth and the V-groove cutting tool angle. Forexample, if the toothed surface (721) has 40 teeth and the groove angleis 60 degrees, an angle θ of about 3.89 degrees will result in the idealmesh. Of course, if the number of teeth changes or the groove anglechanges then θ will be different. As a result, opposing teeth contacteach other along the entire length as shown in section B-B, whichresults in increased strength. This near-perfect mesh is accomplished bychanging the depth of the cutting tool as it cuts the groove.

In yet another embodiment, as illustrated in FIG. 17C, a V-groove is cutat an angle (A) that results in the top edge of the teeth being on thesame plane. This is accomplished by the cutting the V-groove at an angleas shown in section A-A. As before, the angle θ for this embodiment willalso depend on the number of teeth and the V-groove cutting tool angle.For example, again assuming 40 teeth and a groove angle of 60 degrees,an angle θ of about 7.76 degrees will result in an ideal mesh and thetop edge of the teeth being on the same plane. Such a design is ideal ifa washer or plate (725) is disposed between opposing teeth as shown insection B-B because the teeth will embed into the washer or plate (725)evenly, which creates a better grip and even clamping.

In another embodiment, as illustrated in FIG. 17D, a V-groove is cutinto a curved path. In some embodiments, the shape of the curve is aninvolute curve that keeps the width of the teeth constant. During thecutting, the depth is kept constant as shown in section A-A, i.e., thebottom of the groove is flat. By keeping the width and depth of theteeth constant, this configuration results in the top of the teeth beingon the same plane and allows for opposing teeth to have a near-perfectmesh. Thus, the teeth contact each along the entire length. The constanttooth depth makes manufacturing easy and the near-perfect mesh resultsin increased locking strength. If it is desired to use a washer or plate(725) in between the toothed surfaces (721), the fact that the teeth lieon the same plane results in the teeth embedding into the washer orplate (725) evenly, which creates a better grip and even clamping. Ofcourse, the serrated or toothed surface (721) configuration is notlimited to the above embodiments and other configurations can be used.

Because a single bolt (or similar device) is used in the angleadjustment mechanism (720) of the above embodiments, the presentinvention enables rapid and accurate angling of the welding torch (715),which can be particular important for special weld applications in avariety of difficult angles. However, the present invention is notlimited to a single bolt design and any number of bolts (or some otherdesign) can be used so long as the angle α between the weld head (760)and the base unit (750) can be adjusted. In some embodiments, the angleadjustment mechanism (720), weld head (760) and/or the base unit (750)can include scribed lines (723) to enable easy identification of theexact angle α for repeatable set-ups. For example, as illustrated inFIG. 8, the scribed lines (723) are located on weld head (760) and thebase unit (750). Of course, the scribed lines (723) are not limited tothe locations illustrated in FIG. 8 and can be located anywhere on theweld head (760) and/or the base unit (750) so long as the scribed lines(723) identify the angle α.

In some embodiments, the angle adjustment mechanism (720) can enable theAVC assembly (710) stroke direction to be aligned with the orientationof the torch (715). That is, the AVC assembly (710) and the torch (715)are oriented such that the AVC assembly (710) stroke direction asillustrated by arrow 712 in FIG. 7 is perpendicular to the a surface ofthe weld puddle (740). Of course, depending on the application, one orboth of the AVC assembly (710) and the torch (715) can be set at anydesired orientation to the weld puddle (740) and/or the workpieces (705Aand 705B). In exemplary embodiments of the present invention, theorientation of the torch (715) with respect to that of the AVC assembly(710) remains fixed as the angle α between weld head (760) and the baseunit (750) is adjusted. As discussed above, the exemplary angleadjustment mechanism (720) enables a wide swing or rotation range (e.g.,−30° to 110°) of the weld head (760). In some embodiments, the weld head(760) can be set with multiple torch stick-out settings (e.g., two ormore settings) such that the torch (715) can extend to a very long reachand/or provide a large stroke (e.g., a 3½″ AVC stroke). In addition,implementation of the angle adjustment mechanism (720) as discussedabove can also reduce and/or eliminate damaging wear on the angularadjustment mechanism.

In exemplary embodiments, the angle adjustment mechanism (720) can beused to set the orientation of the welding torch (715) with respect tothe weld puddle (740) in a fillet welding application, e.g., asillustrated in FIG. 7. In this case the angle α and the orientation ofthe AVC assemble (710) with respect to the torch (715) are set such thatthe AVC assembly (710) stroke direction and the corresponding torch(715) movement are perpendicular to the surface of the weld puddle(740), as illustrated by arrow 712. As the base unit (750) (or someother device) mechanically oscillates weld head (760) as illustrated byarrow 752 to produce the desired weld weave pattern, the arc length (x)will change if left uncorrected. As in the convention system discussedabove, the AVC assembly (710) can adjust the weld torch (715) positionto maintain the desired arc length (x). However, unlike the conventionalsystem, the AVC assembly (710) stroke direction is aligned such that theAVC assembly (710) moves the welding torch (715) in a direction that isperpendicular to the surface of the weld puddle (740), which allows forbetter control of the arc length (x) across the entire surface of theweld puddle (740). In addition, because AVC assembly (710) strokedirection can stay perpendicular to the weld puddle (740), thesensitivity and speed of the AVC stroke do not need to be adjusted basedon angle α (as they would if the AVC stroke direction stayed vertical).Accordingly, the resulting weld is of a better quality.

In another aspect, the disclosed technology can include an adjustablefillet angle that can enable freedom of motion of an arc voltage control(AVC) assembly, e.g., up to 180 degrees. For example, a singleadjustment can enable rapid and accurate angling of a welding torch,which can be particularly important for special weld applications in avariety of difficult angles.

When an AVC is oriented separate from the torch angle, this can resultin making fillet welds of poor quality. Poor quality welds can alsooccur based on a variety of reasons related to the fillet angle of anAVC assembly, which can include for example insufficient stability ofthe setting (e.g., being insecure and weak), overuse wear and lack ofdurability, limited AVC stroke (e.g., limited to approximately 1 inchAVC stroke), and limited rotation of the AVC assembly (e.g., limited toapproximately 40 degrees).

FIG. 4 shows an exemplary adjustable fillet angle mechanism of an AVCassembly (410) of a weld head tractor unit (400). The exemplaryadjustable fillet angle mechanism can include a built-in serratedlocking mechanism (420) so an exact angle is maintained even under heavyload or abuse. The exemplary locking mechanism enable fillet angleadjustment by single adjustment, e.g., by tightening or loosening a bolt(422) (e.g., a large, heavy duty bolt), such that toothed surfaces (421)connect in a manner that can correspond to the alignment of scribedincrements (423). Scribed increments (423) of the exemplary adjustablefillet angle mechanism can enable easy identification of an exact anglefor repeatable set-ups. Implementation of the exemplary adjustablefillet angle mechanism can enable AVC orientation such that it isaligned with torch angle. The exemplary adjustable fillet anglemechanism can also enable a swing or rotation by a desired angle α(e.g., 140°) of the entire torch assembly with multiple settings (e.g.,three settings) for increasing torch stick-out such that the torch canextend to a very long reach, and provide a large stroke (e.g., a 3½″ AVCstroke). Implementation of the adjustable fillet angle mechanism canalso reduce and/or eliminate damaging wear on angle adjustment of theAVC assembly.

In some exemplary embodiments, the present invention can include alead/lag torch angle adjustment system for a weld held to adjust thelead/lag angle of an electrode. As illustrated in FIG. 9, exemplaryembodiments of the lead/lag torch angle adjustment system can beincorporated in a weld head (905) of welding system (900) that may beused in any of brazing, cladding, building up, filling, hard-facingoverlaying, joining and welding applications. For brevity, only thosecomponents needed to explain the exemplary embodiments of a lead/lagtorch angle adjustment system of a weld head are illustrated anddiscussed. The welding system (900) includes a weld head (905) and awelding base unit (940). The weld head (905) includes a torch assembly(920), a torch head barrel assembly (910), and a torch head supportdevice (930), which can be an arc voltage control (AVC) assembly whenAVC is desired. In the following description, the torch head supportdevice (930) is described in terms of being an AVC assembly (930).However, support device (930) can be another component, e.g., a mountingplate. The torch assembly (920) includes a torch head (921) andelectrode (925) and is operatively connected to the torch head barrelassembly (910). The torch head barrel assembly (910) includes a torchmount (912), a lead/lag torch angle adjustment mechanism (914), and atleast one barrel clamp (916). The torch head barrel assembly (910)operatively connects the torch assembly (920) to the AVC assembly (930),which in turn is operatively connected to the welding base unit (940).Those skilled in the art will recognize that, based on the application,other components such as a wire feeders and wire guides can be connectedto the torch assembly (920) and/or the torch head barrel assembly (910)(see, e.g., FIG. 5B). The torch assembly (920) can be of a type used ongas-shielded tungsten arc welding (GTAW) or plasma arc welding (PAW) inwhich case the electrode (925) can be a tungsten electrode. However, thepresent invention is not limited to GTAW and PAW systems and can beincorporated in other systems such as gas-shielded metal arc welding(GMAW) systems, laser welding systems, etc.

The AVC assembly (930) can include an AVC base unit (936), an AVC slideplate (932), and an AVC assembly control unit (not shown) that isconfigured to maintain a desired arc length (x) extending from the tipof the electrode (925) to workpiece (906). The AVC assembly control unitmaintains the desired arc length (x) by moving the AVC side plate (932)(and torch head barrel assembly (910)) in the direction of arrow (938).The welding base unit (940) can be a mobile unit, e.g., a tractor uniton a track/rail system, or a stationary unit. For example, if theworkpiece (906) is a pipe that is to be welded, the welding base unit(940) can be an orbital tractor drive that is configured to move theweld head (905), including torch assembly (920), along a guide track,e.g., guide track (100) of FIGS. 1A-1C, that is setup around, e.g., acircumferential weld joint of the pipe (either inside or outside of thepipe). Of course, in situations where the weld head (940) is to remainstationary as the workpiece (906) moves, the welding base unit (940) canbe a stationary unit, rather than a drive unit. The welding base unit(940) (or some other device) can be configured to provide mechanicaloscillation as shown by arrow (942) to provide a desired weld weavepattern.

The lead/lag torch angle adjustment mechanism (914) can be operativelyconnected to the support device (930) on the weld head device (905),e.g., an AVC assembly when AVC is desired. In some embodiments, asillustrated in FIGS. 10 and 11A, one end, section (916), of the lead/lagtorch angle adjustment mechanism (914A/B) is attached to or is anintegral part of torch mount (912). The other end, section (915A/B), ofthe lead/lag torch angle barrel mechanism (914A/B) is attached to AVCmount plate (934A/B). Adjustment mechanisms (914A) and (914 B) and AVCmount plate (934A) and (934B) represent different embodiments of theadjustment mechanism (914)/mount plate (934) interface. In adjustmentmechanism (914A) and mount plate (934A), the end section (915A) and themount plate (934A) do not have serrations and in adjustment mechanism(914B) and mount plate (934B), the end section (915B) and mount plate(934B) have serrations (951) (discussed further below). In someembodiments, the end section (915/A/B) and/or at least one barrel clamp(917) (or a similar device) are configured such that a transversemovement of the at least one barrel clamp (917) across the end section(915/A/B) produces a force on the section (915/A/B) such that theadjustment mechanism (914/A/B) is pressed against the AVC mount plate(934/A/B) and locks in the desired lead/lag angle for the electrode(925) with respect to the workpiece. For example, as best seen in FIG.10, the shape of portion (915A) of the adjustment assembly (914A) can beconical and the barrel clamps (917) (or similar devices) can beconfigured to accept the conical shaped section (915A) of the adjustmentmechanism (914A). Accordingly, when the barrel clamps (917) (or similardevices) are attached to the AVC assembly (930), the clamps (917) forcethe lead/lag torch angle adjustment mechanism (914A) against the AVCmount plate (934A) and lock in the desired lead/lag angle. The barrelclamps (917) (or similar devices) can be attached to AVC mount plate(934/A/B), which is attached to or is an integral part of the AVC slideplate (932), by using, e.g., clamping screws or bolts (918) (or otherdevices). By loosing the clamping screws or bolts (918) (or otherdevices), the lead/lag torch angle adjustment mechanism (914/A/B) can berotated to provide for the desired lead/lag angle for electrode (925).In some embodiments, at least one of the lead and the lag angle can havea range of 0 to at least 15°, 0 to at least 90°, or 0 to 180° (i.e., afull 360 degrees of adjustment of the adjustment mechanism (914/A/B)).Of course, the present invention is not limited to a conical shape forthe end section (915/A/B) of adjustment mechanism (914/A/B) and othershapes can be used. In addition, if the welding system does not use anAVC assembly (930), then the end section (915/A/B) of the adjustmentmechanism (914/A/B) can be attached to another type of support device,e.g., a mounting plate (or similar device), that is then attached to thewelding base unit (940).

To aid in setting the lead/lag angle, in some embodiments, theadjustment mechanism (914/A/B) and/or the AVC mount plate (934/A/B) (oranother device) can have alignment lines (952) and (953), respectively(see, e.g., FIGS. 10, 11A, and 11B). The alignment lines (952) and (953)can be, e.g., scribed onto the adjustment mechanism (914/A/B) and/or theAVC mount plate (934/A/B). The alignment lines (952) and/or (953) can bedesignated as a pointer (e.g., see lines (952)) or can indicate desiredincrements (see lines (953). The desired increments can be, e.g., every0.5 degrees or at some other increment. Of course, other methods can beused to display the alignment lines (953). For example, an insert can beinstalled and clearly marked with numbers designating the lead/lagangle, e.g., 1°, 1.5°, 3°, 5°, etc. In some embodiments, the adjustmentmechanism (914/A/B) can rotate the torch assembly (920) with electrode(925) a full 360° to provide a great deal of flexibility in achievingthe desired welding configuration setup, i.e., expands the breadth ofweld setup configurations as compared to conventional systems. Inaddition, in some embodiments, the adjustment mechanism (914/A/B) and/orthe AVC mount plate (934/A/B) can be configured such that there is alocked location in each direction making double-up welding with alead/lag angle very simple. As shown above, the exemplary lead/lag torchangle adjustment mechanism (914/A/B) can be easily accessed to adjustthe lead/lag angle of the torch assembly (920) without marring weld headcomponents. In addition, the barrel clamps (917) provide strong alocking mechanism that fixes the lead/lag angle when the clampingscrews/bolts (918) are tightened.

In some exemplary embodiments, additional locking mechanisms can beincluded so that the angular position of the torch head barrel assembly(910) with respect to the AVC assembly (930)/support device remainsfirmly fixed and the desired lead/lag angle is maintained even underheavy load or abuse. For example, the additional locking mechanisms caninclude serrated or toothed surfaces that interlock when pressedtogether. In some embodiments, at least one serrated or toothed surfaceis built into at least one of the lead/lag torch angle adjustmentmechanism (914) and AVC mount plate (634)/support device. For example,as illustrated in FIGS. 11A and 11C, the end section (915B) ofadjustment mechanism (914B) and AVC mount plate (934B) each have abuilt-in serrated or toothed surface (951). In some embodiments, theserrated or toothed surfaces (951) can directly interlock with eachother. In other embodiments, a washer or plate (950) is disposed betweenthe serrated or toothed surfaces (951). In some embodiments, the washeror plate (950) can be made of a material (e.g., brass, copper, plastic,nylon, etc.) that is softer than that of the serrated or toothedsurfaces (951) such that the serrations embed into the washer or plate(950) to firmly lock the adjustment mechanism (914B) to AVC mount plate(934B). Because the washer or plate (950) can be made of a material thatis softer than that of the serrated or toothed surfaces (951), any signsof wear in the locking mechanism will first be seen by the washer orplate (950). According, because the washer or plate (950) can be made ofinexpensive materials that can be easily replaced after showing signs ofwear, the locking mechanism will remain durable and stable even afterrepeated use. Thus, exemplary embodiments of the present invention canprovide further advantages that include more versatile, stronger lockdown, and fixed lead/lag settings, e.g., at designated (scribed) angles.

Because the lead/lag torch angle adjustment mechanism (914/A/B) can berotated by a single adjustment, e.g., by simply loosening the clampingscrews/bolts (918) (or similar device), the present invention enablesrapid and accurate angling of the torch lead/lag angle and/orre-orientating the torch assembly (920) with electrode (925), which canbe particular important for special weld applications in a variety ofdifficult angles. Further, in some embodiments, the clampingscrews/bolts (918) (or similar device) can be completely unscrewed(removed) such that the lag/lead torch angle adjustment mechanism(914/A/B) (and the torch head barrel assembly (910)) can be easilyattached or detached.

In another aspect, the disclosed technology can include a pivotinglead/lag torch angle mechanism of a torch head barrel assembly on a weldhead device. FIG. 5A shows multiple views of an exemplary weld headsystem (500) that includes an exemplary pivoting lead/lag torch anglemechanism (510). Pivoting lead/lag torch angle mechanism (510) canenable a 360 degree swing of the entire torch (520) by employing arotational angle-locking mechanism at the interface between a torch headbarrel assembly (521) and the remaining portion of weld head system(500). However, the torch head barrel assembly can include an insert(525) to limit the rotation of the lead/lag angle mechanism (510). Forexample, the insert (525) in FIG. 5A, which is marked “5°,” prevents thetorch (520) from rotating more than 5°. FIG. 5B shows multiple views ofan exemplary weld head system (500) that includes a cross-sectional topview showing the pivoting lead/lag torch angle mechanism (510). Pivotinglag/lead torch angle mechanism (510) can include toothed surfaces at theinterface of torch head barrel assembly (521) and the remaining portionof weld head system (500). The toothed surfaces on both sides of theinterface can connect in a manner that can correspond to the alignmentof scribed line alignments (511). Pivoting lag/lead torch anglemechanism (510) can be rotated by single adjustment, e.g., by tighteningor loosening clamping screws (512). Scribed line alignments (511) canallow for a desired alignment. For example, the mechanism can be scribedto easily adjust to a specific angle. An insert can be installed andclearly marked with a number designating the lead/lag angle, e.g., 1°,1.5°, 3°, 5°, etc., such that there is a hard stop in each directionmaking double-up welding with a lead angle very simple. Pivotinglag/lead torch angle mechanism (510) can also allow clamping screws(512) to be completely unscrewed from weld head system (500), which canallow torch head barrel assembly (521) to be attached or detached.

A conventional lead/lag adjustment assembly (barrel assembly) can beassociated with limited angle adjustment, marring of components,slipping of the weld set-up (e.g., because of a weak mechanism of thetorch angle component mechanism), difficult access to make angleadjustments, and inconsistent lead/lag angle settings, among otherlimitations. The exemplary pivoting lead/lag torch angle barrel assemblycan provide a substantially 360 degree swing without any marring, astrong locking mechanism that fixes the lead/lag angle, and easy accessto adjust the angle settings. Pivoting lead/lag torch angle mechanism(510) can expand the breadth of weld set-up configurations. This canprovide further advantages that include more versatile, stronger lockdown, and fixed lead/lag, e.g., at a designated (scribed) angle.

Alternative Track Rail Clamping Embodiment

An alternative embodiment of weld head tractor unit (600) for mountingon a guide track (100) is illustrated in FIGS. 18A-20 and includes atractor mounting mechanism that includes a track rail clamping assembly.The weld head tractor unit (600) is shown in the unclamped position inFIG. 18A and in the clamped position in FIG. 18B.

FIG. 18A illustrates a weld head tractor unit (600) with a tractormounting mechanism that includes a track rail clamping assembly (640),which is shown in the unclamped position in FIG. 18A. As seen in thefront view of the figure, in the unclamped position, the tractor unit(600) has a fixed block (622) and a movable plate (624) that isoperatively connected to wheel/roller set A. The weld head tractor unit(600) can be movably mounted to a guide track (e.g., guide track (100))using a rolling device or rolling devices such as, e.g., wheels and/orrollers. The rail clamping assembly (640) includes a clamping mechanism(640) that is operatively connected to the movable plate (624). To mountor dismount the tractor unit (600), the clamping mechanism (640) ismoved between an open and closed position, thereby adjusting the railclamping assembly (640) to retract wheel/roller set A (see FIG. 18A). Aspart of the exemplary mounting mechanism, in some embodiments, thetractor unit (600) can be clamped or unclamped with the use of a singleclamping action, i.e., by adjusting the clamping mechanism (640) to movewheel/roller set A.

The clamping mechanism (640), illustrated in FIGS. 20A-B, includes ablock (622) that is fixed to the weld head tractor unit (600) and amovable plate (624) that is movable relative to the block (622). Themovable plate (624) is connected to the block (622) by a threaded shaft(626) and one or more cam springs (628) that force the movable plate(624) away from the block (622). Use of the term “spring” herein willinclude any assembly capable of applying a biasing force including butnot limited to linear springs, coil springs, pneumatic or hydrauliccylinders, inflatable bladders, resilient structures or materials, andthe like. Therefore the particular embodiments shown in the drawings anddescribed herein should not be considered limiting. Likewise, referenceto a “spring” force or “spring” constant will be understood to includethe biasing force, which may be constant or variable, and biasingconstant, when constant, provided by a particular biasing assembly,component, or structure.

The shaft (626) includes a first end threaded into the fixed block (622)and a second end extending through the movable plate (624) and having anaxle (630) passing therethrough. A cam handle (632) is attached to theaxle (630) and is movable between a first, open position (FIG. 20A) anda second, closed position (FIG. 20B). As shown in FIGS. 20A-B, the camhandle (632) rotates 180° about the axle (630) between the open andclosed positions, but other angles of rotation are contemplated.

When the cam handle (632) is in an open position (FIG. 20A), the camportion allows the movable plate to sit farther away from the fixedblock (624) as the cam springs (628) force the movable plate (624) awayfrom the fixed block (622). In this position, the distance between thewheel/roller sets (A, B) is maximized and the weld head tractor unit(600) may be connected to the track (100).

When the cam handle (632) is moved to a closed position (FIG. 20B) thecam portion forces the movable plate (624) towards the fixed block(622). This causes the distance between the wheel/roller sets (A, B) todecrease, compressing the cam springs (628) and thereby connecting theweld head tractor unit (600) to the track (100) as described above.

An additional over-clamping spring (634) may be provided between the camhandle (632) and the movable plate (624) that prevents the cam frombottoming out and allows the cam handle (632) to completely close if themovable plate (624) is flush to the fixed block (622) or if the rollershave already made contact with the track before the cam has reached theclosed position. The over-clamping spring (634) typically has a veryhigh spring force relative to the spring force of the cam springs (628)so that the cam springs (628) are compressed prior to the over-clampingspring (634). The over-clamping spring (634) will be provided withsufficient stiffness so that the weld head still clings firmly to thetrack when the cam handle (632) is in the closed position. Theover-clamp spring (634) may also be useful in allowing the tractor unit(600) to be attached to a track (100) having some variation in the trackwidth. In this instance, the tractor unit (600) is placed on thenarrowest track width and the cam handle (632) is closed. As the track(100) widens, the over-clamp spring (634) will compress, compensatingfor the difference in track width.

Linear bearing assemblies (consisting of a shaft and a linear bearing)(636) may also be provided between the fixed block (622) and movableplate (624) to guide linear movement and reduce friction and wear duringmovement of the movable plate (624) relative to the fixed block (622).

Adjustment of the distance between the fixed block (622) and movableplate (624) may be provided by adjusting the position of the threadedshaft (626) and axle (630) relative to the fixed block (622).

In a first adjustable embodiment, the threaded shaft (626) may bethreaded into the movable block (622) and have an adjustable threadeddepth. In order to increase the distance between the fixed block (622)and movable plate (624) when the cam handle (632) is in a closedposition, the shaft (626) may be threaded into or removed from the fixedblock (622). By turning the shaft, the distance between the axle (630)and fixed block (622) may increase or decrease, fixing the distancebetween the wheels/rollers (A,B) in the closed position.

It may be desired that the axle (630) be provided at a preferredorientation (e.g. perpendicular to the track (100)). According to thefirst adjustable embodiment, with the axle (630) in a fixed orientationrelative to the shaft (626), the shaft (626) may only be screwed into orout of the fixed block (622) in half-rotation increments in order tomaintain the axle (630) at the preferred orientation. For a shaft (626)having a thread pitch of 32 TPI (0.03125 inches/revolution) (0.8mm/revolution), the distance between the axle (628) and fixed block(622) can only be adjusted in increments of 0.015625″ (0.4 mm). Thislevel of adjustment may not be acceptable for fine control, andtherefore other methods of fine adjustment may be provided.

In a second adjustable embodiment, the shaft (626) may have a firstthreaded end and a second threaded end with the axle (630) threaded ontothe second threaded end. The first threaded end and second threaded endare provided with opposite (e.g. right- and left-hand) threading so thatas the shaft (626) is threaded into the fixed block (622) the axle (630)may be threaded in the opposite direction, maintaining the preferredorientation. This arrangement allows for finer adjustment of the axle(630) as the shaft (626) is not limited to fixed increments.

In a third adjustable embodiment, the shaft (626) may have a firstthreaded end and a second threaded end with the axle (630) threaded ontothe second threaded end. The first threaded end and the second threadedend are provided with different thread pitches. With the different pitchthread configuration, the displacement of the axle (626) is equivalentto the difference of the pitches. In one case, the first pitch may be 32TPI (0.03125 inches/revolution) and the second may be 24 TPI (0.04167inches/revolution), and therefore the displacement is 0.01042 inches perrevolution (equivalent to 96 TPI). By making the pitches on either endcloser, the adjustment will be finer.

All of the adjustable embodiments described above may also be providedwith a locking feature for locking the shaft and axle in place once theadjustment is set. Set screws may be used for this purpose, although itwill be apparent that other locking features may be used.

While this patent document contains many specifics, these should not beconstrued as limitations on the scope of any invention or of what may beclaimed, but rather as descriptions of features that may be specific toparticular embodiments of particular inventions. Certain features thatare described in this patent document in the context of separateembodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to a subcombination or variation of a sub combination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Moreover, the separation of various system components in theembodiments described above should not be understood as requiring suchseparation in all embodiments.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this patent document.

In summary, while the invention has been described with reference tocertain embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substitutedwithout departing from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the invention without departing from its scope.Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed, but that the invention will includeall embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A mounting mechanism for connecting a weld headtractor unit to a guide track, comprising: a fixed block having a firstset of rolling devices; a movable plate having a second set of rollingdevices, the movable plate movable to adjust the distance between saidfirst and second set of rolling devices; a clamping assembly having ashaft extending from said fixed block and through said movable plate, acam spring between said fixed block and said movable plate, a cam handlepivotally connected to said shaft and movable between an open positionfor disengaging said tractor unit to said guide track and a closedposition for engaging said tractor unit to said guide track, the guidetrack comprising a first rail and a second rail, an axle between the camhandle and the shaft, wherein, when the cam handle is in the openposition, the distance between the first and second set of rollingdevices is greater than a width of the guide rail, and wherein when thecam handle is in the closed position, the distance between the first andsecond set of rolling devices is approximately equal to the width of theguide rail, and wherein the shaft includes a first threaded portion forengaging the fixed block such that rotation of the shaft adjusts adistance between the axle and the fixed block, and an orientation of theaxle relative to the guide track is adjustable.
 2. The mountingmechanism of claim 1 wherein the axle is adjustably threaded to saidshaft.
 3. The mounting mechanism of claim 2 wherein the shaft includes asecond threaded portion for receiving the axle.
 4. The mountingmechanism of claim 3 wherein one of the first and second threadedportions is right-hand threaded and the other of the first and secondthreaded portion is left-hand threaded.
 5. The mounting mechanism ofclaim 3 wherein the first threaded portion has a first pitch and thesecond threaded portion has a second pitch that is different from thefirst pitch.
 6. The mounting mechanism of claim 1 further comprising anover-clamp spring between said cam handle and said movable plate.
 7. Themounting mechanism of claim 6 wherein a stiffness of said over-clampspring is greater than a stiffness of said cam spring.
 8. The tractorunit mounting mechanism of claim 1, wherein the first set of rollingdevices and the second set of rolling devices are designed to roll onsaid track.
 9. The tractor unit mounting mechanism of claim 1 whereineach of the first and second set of rolling devices comprises one ormore pivot blocks and one or more rollers on each of said pivot blocks.10. The tractor unit mounting mechanism of claim 9 wherein each of thepivot blocks is configured to pivot such that the rollers of therespective pivot blocks can conform to a profile of the guide track asthe tractor unit is engaging the guide track.
 11. The tractor unitmounting mechanism of claim 10, wherein the clamping assembly isconfigured to operatively connect the rollers of each of the first pivotblock and the second pivot block with the guide track when clampingassembly is in the closed position.
 12. The tractor unit mountingmechanism of claim 11, wherein each of the first pivot block and thesecond pivot block comprises a locking mechanism that is configured toprevent the respective pivot blocks from pivoting once the tractor unithas engaged the guide track.
 13. The tractor unit mounting mechanism ofclaim 12, wherein the locking mechanism is a bushing.
 14. The tractormounting mechanism of claim 13, wherein the bushing is disposed suchthat friction prevents the pivot block from pivoting when the tractorunit has engaged to the guide track.
 15. The tractor mounting mechanismof claim 1, wherein the profile of the guide track is one of a concaveprofile, convex profile, a straight profile, or any combination thereof.16. The tractor mounting mechanism of claim 1, wherein sizes of thefirst rail and the second rail of the guide track are between 1/16 inchto 2 inches, inclusive, and wherein shapes of the first rail and thesecond rail includes one of round, square, triangle, and octagonal. 17.A mounting mechanism for connecting a weld head tractor unit to a guidetrack, comprising: a fixed block having a first set of rolling devices;a movable plate having a second set of rolling devices, the movableplate movable to adjust the distance between said first and second setof rolling devices; a clamping assembly having a shaft extending fromsaid fixed block and through said movable plate, a cam spring betweensaid fixed block and said movable plate, a cam handle connected to saidshaft and movable between an open position for disengaging said tractorunit to said guide track and a closed position for engaging said tractorunit to said guide track, the guide track comprising a first rail and asecond rail, an axle between said cam handle and said shaft, wherein,when the cam handle is in the open position, the distance between thefirst and second set of rolling devices is greater than a width of theguide rail, wherein when the cam handle is in the closed position, thedistance between the first and second set of rolling devices isapproximately equal to the width of the guide rail, and wherein theshaft is adjustably threaded into said fixed block such that rotation ofthe shaft adjusts a distance between the axle and the fixed block, andan orientation of the axle relative to the guide track is adjustable.